1. Field of the Invention
The present invention relates to an electric work vehicle including right and left motors, which are charged and powered by a battery, in which the right motor drives a right rear wheel and the left motor drives a left rear wheel to propel the vehicle in operation.
2. Description of the Related Art
A conventional lawn mower is disclosed in WO 2013/015171 A1 (FIGS. 1 and 2). This lawn mower includes a pair of right and left rear wheels driven independently of each other by a pair of right and left motors, respectively. The right and left rear wheels are supported by a rear axle casing extending between the rear wheels. A gear casing extends from a central part of the rear axle casing at right angles relative to an extending direction of the rear axle casing. The right motor is provided in a right side of an extreme end of the gear casing, and the left motor is provided in a left side of the extreme end of the gear casing. The right and left motors extend in a vehicle lateral direction. Rotary power from each of the motors is transmitted to an axle which is housed in the rear axle casing through a transmission mechanism housed in the gear casing. As apparent from FIG. 2 in WO 2013/015171 A1, the right and left motors extending straight in the vehicle lateral direction are connected to the rear axle casing which is also extending straight in the vehicle lateral direction, via the gear casing extending in a vehicle fore/aft direction along a vehicle lateral centerline. Thus, the casing structure disclosed in WO 2013/015171 A1 housing the mechanism for transmitting power from the motors to the rear wheels has a significantly complicated configuration, which results in increased costs. Further, the right and left motors are mounted inward of a vehicle frame and a battery is disposed between the right and left motors, which disadvantageously results in unavailability of a large battery.
JP 2008-168869 A (or US 2009/00008391 A1 corresponding thereto) discloses a conventional hybrid lawn mower including a right motor for driving a right rear wheel and a left motor for driving a left rear wheel, which are attached to outer sides of a frame; and an engine and a battery, which are mounted between the right and left motors. The right and left motors are wheel motors each having a rotary axis aligned with a rear wheel axis. In this arrangement, the heavy engine and battery are disposed rearward of the rear wheel axis, which results in poor balance relative to the rear wheel axis. On the other hand, no improvement has been achieved on such a precarious vehicle balance, since each of the right and left motors has a center of gravity thereof substantially on the rear wheel axis.
Under these circumstances, it has been desired that an electric work vehicle, including a right motor for driving a right rear wheel and a left motor for driving a left rear wheel, should improve the vehicle balance and secure a sufficient space for a large battery.